Hi Fl, you stuck up for me. Once! I will give you some info, get the book Understanding Ballistics by Robert A. Rinker. Lots of info and very educational. If you get the book watch out for some of the math, it is basic math but if your answers do not make sence you have convert into grains. For example on how to figure out recoil he mentions rifle weight. You have to convert the weight of your rifle into grains not pounds. Great book but at times confusing. The book gets into everything and for a person into ballistics very well worth the money!!!!